Journal of Chemical Ecology

, Volume 35, Issue 11, pp 1309-1319

First online:

Same Host-Plant, Different Sterols: Variation in Sterol Metabolism in an Insect Herbivore Community

  • Eric M. JansonAffiliated withDepartment of Biological Sciences, Vanderbilt University Email author 
  • , Robert J. GrebenokAffiliated withDepartment of Biology, Canisius College
  • , Spencer T. BehmerAffiliated withDepartment of Entomology, Texas A&M University
  • , Patrick AbbotAffiliated withDepartment of Biological Sciences, Vanderbilt University

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Insects lack the ability to synthesize sterols de novo, which are required as cell membrane inserts and as precursors for steroid hormones. Herbivorous insects typically utilize cholesterol as their primary sterol. However, plants rarely contain cholesterol, and herbivorous insects must, therefore, produce cholesterol by metabolizing plant sterols. Previous studies have shown that insects generally display diversity in phytosterol metabolism. Despite the biological importance of sterols, there has been no investigation of their metabolism in a naturally occurring herbivorous insect community. Therefore, we determined the neutral sterol profile of Solidago altissima L., six taxonomically and ecologically diverse herbivorous insect associates, and the fungal symbiont of one herbivore. Our results demonstrated that S. altissima contained Δ7-sterols (spinasterol, 22-dihydrospinasterol, avenasterol, and 24-epifungisterol), and that 85% of the sterol pool existed in a conjugated form. Despite feeding on a shared host plant, we observed significant variation among herbivores in terms of their qualitative tissue sterol profiles and significant variation in the cholesterol content. Cholesterol was absent in two dipteran gall-formers and present at extremely low levels in a beetle. Cholesterol content was highly variable in three hemipteran phloem feeders; even species of the same genus showed substantial differences in their cholesterol contents. The fungal ectosymbiont of a dipteran gall former contained primarily ergosterol and two ergosterol precursors. The larvae and pupae of the symbiotic gall-former lacked phytosterols, phytosterol metabolites, or cholesterol, instead containing an ergosterol metabolite in addition to unmetabolized ergosterol and erogsterol precursors, thus demonstrating the crucial role that a fungal symbiont plays in their nutritional ecology. These data are discussed in the context of sterol physiology and metabolism in insects, and the potential ecological and evolutionary implications.


Nutritional ecology Phytosterols Plant-insect interactions Solidago altissima Spinasterol Cholesterol